Simple adaptive control system design trades

In the design of a Model Reference Adaptive Control system, a reference model serves as the (well-known) basis through which system and user requirements can find their way into the design. By tuning the design parameters, the response of the actual vehicle should track the response of the reference model as well as possible. In the current study, the actual vehicle is an unpowered, winged re-entry vehicle similar to the Space Shuttle. To understand the influence of each of the design parameters on the controller performance, a sensitivity analysis is conducted on sample frequency, weighting-matrix coefficients and compensator parameters. Also the influence of varying flight conditions is studied. Normalisation of the reference signals has led to a more unified definition of the design parameters, and has introduced more independence from the flight conditions. Even though the influence of the design parameters is well understood, the large number makes tuning them a tedious process. An automated optimisation procedure should be used, since the interaction between the related design parameters makes an all-in-one-go approach mandatory. Experience of the designer, though, can easily reduce the design time, if a sub-optimal yet satisfactory response is strived for.